(1) Field of the Invention
The present invention relates to an improved trimming apparatus for a blow molded container. In particular, the present invention relates to a trimming apparatus for removing an upper dome scrap from a blow molded plastic container, such as a plastic bottle. The conventional blow molding machines produce a blow molded plastic bottle having dome scrap which extends above the opening of the bottle. The dome scrap must be removed in such a way as to provide a smooth, clean cut opening on the bottle.
(2) Description of Related Art
The related art shows several apparatus for trimming bottles which use rotation of the bottle. Illustrative are U.S. Pat. No. 3,429,211 to Pelot and U.S. Pat. Nos. 4,445,406 and 4,876,930 both to Thatcher.
Several related art trimming apparatus have rotating devices such as a rotating wheel or a turret that rotates a hollow, plastic bottle in an arcuate path past a stationary knife edge to trim dome scrap from the bottle. This type of device is illustrated in U.S. Pat. No. 3,675,521 to Ziegler; U.S. Pat. No. 3,800,638 to Duikers et al; U.S. Pat. Nos. 3,894,454 and 3,962,938 both to Reilly et al; U.S. Pat. No. 3,886,824 to Michel et al; U.S. Pat. No. 3,967,516 to Griesing et al and U.S. Pat. No. 4,614,018 to Krall. In particular Griesing et al describes a trimming apparatus having a rotating wheel that moves the bottle in an arcuate path along a fixed guide while a rotating blade trims the dome scrap from the bottle.
In addition, Reilly et al ('454) shows an apparatus for deflashing thermoplastic articles. In operation, the untrimmed preforms are dropped at the inlet end of the apparatus and are supported by their hot moil portions between the screw conveyor and the adjacent support. The screw conveyor keeps the hot preforms spaced apart as it sequentially advances the preforms toward the deflashing station. The preforms rotate about their vertical axes as they move. The preforms are passed into the moil cutting pattern in the deflashing station where they are rollingly engaged by a wheel which urges the moil portion into and against the knife edge so as to slice through the plastic in a substantially lateral direction. The cutting surface has the same arcuate shape as the wheel. The unsupported, trimmed preforms fall by gravity in through a tapering funnel on and to a carrier assembly. Reilly et al ('938) shows a similar apparatus.
These trimmer apparatus tend to be extremely complicated, which can translate into substantial down time for a production line if a part of the apparatus malfunctions.
Other types of trimming and cutting apparatus are shown by U.S. Pat. No. 3,541,905 to Mey; U.S. Pat. No. 3,728,063 to Langecker and U.S. Pat. No. 3,352,404 to Settembrini. Mey describes a device for radially cutting tubular workpieces to form piston rings or cylinder liner blanks, and the like. Langecker describes an apparatus that removes neck waste from a hollow plastic bottle with a striker operated by a piston-cylinder mechanism. Settembrini is only generally related to the present invention and describes an air-pervious conveyor belt for maintaining a plastic bottle on a conveyor belt in a stable position.
My U.S. Pat. No. 5,257,560 describes a trimmer for removing scrap from the tops of plastic bottles. The trimmer uses a pair of rotating belts which create a path through the apparatus and which move and spin the bottle along the path of the trimmer. As the bottle moves and spins along the path between the belts, the bottle moves past a stationary knife which cuts and removes the dome scrap of the bottle.
There remains a need for a trimmer apparatus for blow molded, plastic bottles that is relatively simple in construction and which rotates the bottle adjacent the knife which removes the dome scrap from the bottle as the bottle moves down a longitudinal path through the trimmer apparatus.